Easy but dangerous, as I know from personal experience :-(( If you trade online at your broker's or the other sites, such as Chas Schwab, you can get into huge trouble and do it at any time of day or night. That influences stock price. Transferring funds from money market or bank is made - surprise, surprise-very simple.. I had a MM at Vanguard and bought several tech stocks the day they hit their highest price. Caveat.....